Matte drafting films have long been used as media for engineering drawings, and their compositions are well known in the art. Conventional drafting film construction consists of an underlayer and an overlying surface layer on at least one side of a base support such as polyethylene terphthalate. Pencil tooth for drafting purposes is obtained primarily through the underlayer which is comprised of a finely divided pigment dispersed within a cross-linked binder. The surface layer is comprised of a polymeric matrix which provides ink receptivity and adhesion, and also pencil and ink erasability. At times, the surface layer employs an antistatic agent to reduce static charge to correct the problem of static cling and attraction of foreign matter.
More recently, use of matte drafting surfaces have also been provided on the opposing side of electronically imaging media which has placed additional requirements on the drafting surface. These requirements include the following: (1) Effective inhibition of dust and dirt attraction due to static electricity. Static is particularly serious in electronic imaging processes, because dust or foreign matter will frequently cause voids and consequent loss of information. (2) Inhibition of spurious electrostatic charges which cause toner background problems, especially in electrostatic printing. (3) Reliable transport and stacking in automated imaging devices. (4) Good toner adhesion in electrophotographic imaging processes where the matte drafting surface is the imaged side. (5) Reduction in the number of layers in the matte or drafting matrix to help reduce cost and improve quality control.
Antistatic agents have long been used as a means of reducing static charge in a variety of applications. In the past, however, the use of antistatic agents in drafting media have often been accompanied by undesirable properties which has discouraged their use in such media. This has been particularly true with respect to newer electronic copying and printing applications.
The literature abounds in the listing of antistats and their applications. These antistats may be broadly classified as cationic, anionic and non-ionic. The cationic classification includes protonated amines and quaternary ammonium, sulfonium and phosphonium cations. The quaternary ammonium cations may be divided into six different sub-classes of varying structure and molecular weight. While there is an enormous diversity of both molecular structure and applications for antistats, there is little teaching to be found as to which are most appropriate for drafting surfaces. Most work for the drafting application has been empirical and has addressed a rather narrow set of product performance requirements.